Endovascular aneurysm repair system

ABSTRACT

Method and apparatus for implanting radially expandable prostheses in the body lumens rely on tacking or anchoring of the prostheses with separately introduced fasteners. The prostheses may be self-expanding or balloon expandable. After initial placement, a fastener applier system is introduced within the expanded prostheses to deploy a plurality of fasteners at least one prosthesis end, usually as each end of the prosthesis. The fasteners are usually helical fasteners which are delivered from a helical track in the fastener applier by rotation with a rotator wire. The fasteners will be applied singly, typically in circumferentially spaced-apart patterns about the interior of each end of the prosthesis.

RELATED APPLICATION

This application is a divisional of co-pending U.S. patent applicationSer. No. 10/271,334 filed Oct. 15, 2002, which claims the benefit ofU.S. provisional application Ser. No. 60/333,937 filed 28 Nov. 2001.

BACKGROUND OF THE INVENTION

The invention relates generally to the attachment of a vascularprosthesis to a native vessel, and in particular, to a method and systemof devices for the repair of diseased and/or damaged sections of avessel.

Description of Related Art. The weakening of a vessel wall from damagedor diseased can lead to vessel dilatation and the formation of ananeurysm. Left untreated, an aneurysm can grow in size and willeventually rupture.

For example, aneurysms of the aorta primarily occur in abdominal region,usually in the infrarenal area between the renal arteries and the aorticbifurcation. Aneurysms can also occur in the thoracic region between theaortic arch and renal arteries. The rupture of an aortic aneurysmresults in massive hemorrhaging and has a high rate of mortality.

Open surgical replacement of a diseased or damaged section of vessel caneliminate the risk of vessel rupture. In this procedure, the diseased ordamaged section of vessel is removed and a prosthetic graft, made eitherin a straight of bifurcated configuration, is installed and thenpermanently attached and sealed to the ends of the native vessel bysuture. The prosthetic grafts for these procedures are usuallyunsupported woven tubes and are typically made from polyester, ePTFE orother suitable materials. The grafts are longitudinally unsupported sothey can accommodate changes in the morphology of the aneurysm andnative vessel. However, these procedures require a large surgicalincision and have a high rate of morbidity and mortality. In addition,many patients are unsuitable for this type of major surgery due to otherco morbidities.

Endovascular aneurysm repair has been introduced to overcome theproblems associated with open surgical repair. The aneurysm is bridgedwith a vascular prosthesis, which is placed intraluminally. Typicallythese prosthetic grafts for aortic aneurysms are delivered collapsed ona catheter through the femoral artery. These grafts are usually designedwith a fabric material attached to a metallic scaffolding (stent)structure, which expands or is expanded to contact the internal diameterof the vessel. Unlike open surgical aneurysm repair, intraluminallydeployed grafts are not sutured to the native vessel, but rely on eitherbarbs extending from the stent, which penetrate into the native vesselduring deployment, or the radial expansion force of the stent itself isutilized to hold the graft in position. These graft attachment means donot provide the same level of attachment when compared to suture and candamage the native vessel upon deployment.

Accordingly, there is a need for an endovascular aneurysm repair systemthat first provides a prosthetic graft, which can adapt to changes inaneurysm morphology and be deployed without damaging the native vesseland second, a separate endovascular fastening system that providespermanent graft attachment to the vessel wall.

SUMMARY OF THE INVENTION

The methods and apparatus for implanting radially expandable prosthesesis the body lumens are described. In particular, the present inventionprovides improved methods and systems for implanting vascular stents andstent-grafts into blood vessels, including both arterial and venoussystems. In the exemplary embodiments, stent-grafts are placed invasculature to reinforce aneurysms, particularly abdominal aorticaneurysms.

In the first aspect of the present invention, a radially expandableprosthesis is placed in a body lumen by first expanding at least onescaffold of the prosthesis at or near an implantation site within thebody lumen, e.g., at or from vasculature on one side of an aneurysm.After expanding the scaffold of the prosthesis, a plurality of fastenersare introduced through the prosthesis in the region in the scaffold toanchor the scaffold in place. The scaffold may be elastic, typicallycomprised of a shape memory alloy elastic stainless steel, or the like.For elastic scaffolds, expanding typically comprises releasing thescaffolding from constraint to permit the scaffold to self-expand at theimplantation site. The constraint may be radial constraint, i.e.,placement of a tubular catheter, delivery sheath, or the like over thescaffold in order to maintain the scaffold in a radially reducedconfiguration. Expansion is then achieved by pulling back on thecatheter sheath to permit the scaffold to return to its larger diameterconfiguration. Alternatively, the scaffold may be constrained in anaxially elongated configuration, e.g., by attaching either end of thescaffold to an internal tube, rod, catheter or the like, to maintain thescaffold in the elongated, reduced diameter configuration. The scaffoldmay then be released from such axial constraint in order to permitself-expansion.

Alternatively, the scaffold may be formed from a malleable material,such as malleable stainless steel of other metals. Expansion may thencomprise applying a radially expansive force within the scaffold tocause expansion, e.g., inflating a scaffold delivery catheter within theside of the scaffolding order to affect the expansion.

The vascular prosthesis may have a wide variety of conventionalconfigurations. In the preferred placement of the vascular stent-graft,prosthesis would typically comprise a fabric other bloodsemi-impermeable flexible barrier which is supported by a scaffold,typically in the form of a stent. A stent can have any conventionalstent configurations, such as zigzag, serpentine, expanding diamond, orcombinations thereof. The stent structure may extend the entire lengthof the graft, and in some instances will be longer than the fabriccomponents of the graft. Alternatively, the stent will cover only asmall portion of the prosthesis, e.g., being present on at 1,2, or 3ends. The stent may have three or more ends when it is configured totreat bifurcated vascular regions, such as the treatment of abdominalaortic aneurysms when the stent graft extends into the iliac arteries.In certain instances, the stents may be spaced apart along the entirelength, or at least a major portion of the entire length, of thestent-graft, where individual stent structures are not connected to eachother directly, but rather connected to the fabric or other flexiblecomponent of the graft.

Introduction of the fasteners will typically be effected after theprosthesis has been initially placed. That is initial placement will beachieved by self-expansion or balloon expansion, after which theprosthesis is secured or anchored in place by the introduction of aplurality of individual fasteners, preferably helical fasteners whichare rotated and “screwed into” the prosthesis and vessel wall. Fastenersmay be placed through the fabric only, i.e., avoiding the scaffoldstructure. Alternately, the fasteners can be introduced into and throughportions of the scaffold structure, optionally through receptacles orapertures which have been specially configured to receive the fasteners.In some cases, of course, fasteners will be introduced both through thefabric and through of over the scaffold structure.

In the exemplary embodiment, the fasteners are helical fasteners, whichare introduced singly, i.e., one at a time, in a circumferentiallyspaced-apart pattern over an interior wall of the prosthesis. Usually,the fasteners will be introduced using a fastener applier which carriesa single fastener. Fastener appliers which carry a single fastener canhave a lower profile and may be more effective and less traumatic thanfastener appliers which carry multiple fasteners. The present invention,however, does contemplate that in certain embodiments the fastenerapplier may carry multiple fasteners. Moreover, the fastener applier maysimultaneously deploy multiple fasteners in the preferredcircumferentially spaced-apart space pattern described above. Usually,from 2-12 fasteners will be applied at each end of the prosthesis to beanchored. The 2-12 fasteners will usually be applied in a singlecircumferentially space-apart row that may be applied in more than onerow with individual fasteners being axially aligned or circumferentiallystaggered. In a preferred embodiment, the intraluminal fastener applierof the present invention comprises a guide component and an appliercomponent. The guide component, for example, comprises a tubular bodyhaving a deflectable distal tip and, optionally, a stabilizer forholding the deflected tip against a location in the graft to which thefastener is to be applied. The applier component is insertable through alumen of the guide component and carries at least a single helical orother fastener. A rotation driver is provided for rotating and advancingthe helical fastener so that it penetrates the graft and underlyingvessel wall to anchor the graft firmly in place.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood from the following detailed descriptionof preferred embodiments, taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of one embodiment of an endovascular graftdelivery device shown positioned within an abdominal aortic aneurysm;

FIG. 2 is a perspective view of one embodiment the deployment of anendovascular graft within the aneurysm of FIG. 1;

FIG. 3 is a perspective view of a fully deployed straight endovasculargraft of FIG. 2;

FIG. 4 is a perspective view of a fully deployed bifurcated endovasculargraft broken away to show an anchoring scaffold at one end;

FIG. 5 is a perspective view similar to FIG. 5 showing an alternativescaffold structure;

FIG. 6 is a perspective view showing one embodiment of a device fordirecting the fastener applier;

FIG. 7 is a perspective view showing the device of FIG. 6 upon insertionwithin the deployed endovascular graft of FIG. 3 with both the graft andscaffolding broken away;

FIG. 8 is a perspective view of the device of FIG. 6 showing activationof one embodiment of a stabilizing device attached to the directingdevice;

FIG. 9 is a perspective view of the control assembly in FIG. 8articulating the directing device of FIG. 6;

FIG. 10 is a perspective view of an alternative embodiment of thestabilization device of FIG. 8;

FIG. 11 is a perspective view showing the activation of the alternativestabilization device of FIG. 10;

FIG. 12 is a perspective view showing another embodiment of thestabilization device of FIG. 8;

FIG. 13 is a perspective view showing activation of the stabilizationdevice of FIG. 12;

FIG. 14 is one embodiment of the fastener applier;

FIG. 15 is a perspective view of the fastener applier of FIG. 14 beingpositioned within directing device of FIG. 6;

FIG. 16 is an enlarged cross-sectional view of one embodiment of thefastener applier of FIG. 14;

FIG. 17 is an enlarged cross-sectional view of the attachment appliershowing one embodiment of the proximal end of the helical fastener andthe drive mechanism;

FIG. 18 is a enlarged perspective view of one embodiment of the helicalfastener of FIG. 16;

FIG. 19 is an enlarged view of the attachment applier showing oneembodiment of the control assembly that activates the fastener applier;

FIG. 20 is an enlarged view of the attachment applied activated with afastener implanted into the graft and vessel wall;

FIG. 21 is an enlarged view of the completed attachment of the proximalgraft of FIG. 3 to the vessel wall with fasteners;

FIG. 22 is a perspective view of the graft of FIG. 4 completely attachedto the vessel.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts an endovascular graft delivery catheter 10 beingpositioned within an abdominal aortic aneurysm 11 over a guidewire 12.FIG. 2 depicts the initial stage of graft deployment within a vessel.The delivery catheter 10 has a movable cover 13 over the graft. When thecover is pulled proximally the graft 14 expands to contact the internalwalls of the vessel. It is contemplated that the graft could beself-expanding or utilize an expanding member such as a balloon ormechanical expander. The process of graft deployment is continued untilthe graft is fully deployed within the vessel. It is contemplated thatthe graft could be in either a straight or bifurcated form. FIG. 3depicts a completely deployed straight graft 14 and FIG. 4 depicts acompletely deployed bifurcated graft 15. The guidewire 11 used todeliver and position the graft remains within the vessel for access ofthe fastener attachment system. One embodiment of the graft scaffolding16 (stent) is illustrated in the area broke away in FIG. 4. The stent isin the form of a simple zigzag pattern, however it is contemplated thatthe stent design could involve more complex patterns 17 as depicted inFIG. 5. Although only one stent structure within the graft is depicted,in FIGS. 4 and 5, it is contemplated that multiple independent stentstructures could be incorporated into the graft. 1391 FIG. 6 depicts oneembodiment of the directing device 18 with an obturator 19 positionedwithin the lumen of the directing device and extending past the distalof the tip of the directing device. The obturator has a lumen to allowfor delivery over a guidewire. FIG. 7 depicts the directing device beingpositioned within the deployed endovascular graft over a Quidewire 12.The directing device has an incorporated stabilizing device 20 to aid inmaintaining position of the directing device within the vessel. In oneembodiment, the stabilizing device 20 is spring-loaded and is positionedfor use when the obturator in the directing device is removed FIG. 8.The directing device is activated though a control assembly 21 as seenin FIG. 8. In one embodiment the control assembly 21 features a movablewheel or lever 22, which deflects the distal tip 23 of the directingdevice 18 to the desired location as seen in FIG. 9. It is contemplatedthat the control assembly for the directing device could be activatedmechanically, electrically, hydraulically or pneumatically. The controlassembly has a through lumen to allow for the passage of the obturatorand fastener applier. FIG. 10 depicts another embodiment the stabilizingdevice as a movable strut assembly 24. The movable strut assembly isactivated through a lever 25 on the control assembly FIG. 11. In bothembodiments (FIGS. 7 and 10) the stabilizing device is distal to the endof the directing device. In another embodiment the stabilizing devicecould be in the form of an expandable member 26 adjacent to the distaltip of the directing device FIG. 12. In one embodiment, the expandablemember 26 is shown activated through a lever 25 on the control assemblyFIG. 13. However it also contemplated that this type of stabilizingdevice could also be inflatable. In all embodiments the stabilizingdevice could be use to stabilize the directing member eitherconcentrically or eccentrically within the vessel.

In another embodiment of the invention a separate tubular device couldbe used in cooperation with the directing device and to access thevessel. This separate tubular device could incorporate the stabilizingdevices used above with the directing device.

FIG. 14 depicts one embodiment of the fastener applier 27. FIG. 14A is adetail view of the distal end of the fastener applier. FIG. 15 depictsthe fastener applier being positioned through the lumen of the directingdevice to the site where a fastener will be installed.

FIG. 16 is an enlarged cross-sectional view of fastener applier 27 anddirecting device 18. In one embodiment of the fastener applier thehelical fastener 28 is rotated via a fastener driver 29 through a driveshaft 30 that is connected to the control assembly 31. The drive shaft30 can be made of any material that allows for both bending androtation. The drive shaft is connected to the fastener driver 29, whichengages and imparts torque to the helical fastener. FIG. 16 illustratesthe coils of the helical fastener 28 engaged with internal grooves 32within the fastener applier. It is contemplated that the grooves couldbe positioned along the entire length of the fastener or within aportion of its length. FIG. 17 is an enlarged cross-sectional view ofthe fastener applier 27 with a cross-section of the fastener driver 29depicting one embodiment of engagement between the fastener driver andhelical fastener 28. In this embodiment the proximal coil of the helicalfastener is formed to produce a diagonal member 33, which crosses thediameter of the helical fastener. Similar helical fasteners aredescribed in U.S. Pat. No. 5,964,772; 5,824,008; 5,582,616; and6,296,656, the full disclosures of which are incorporated herein byreference.

FIG. 18 depicts one embodiment of the helical fastener 28 showing thediagonal member 33. FIG. 19 depicts one embodiment of the fastenerapplier 27 during activation of the fastener applier control assembly.Activation of the control assembly rotates the drive shaft, fasterdriver and helical fastener. This rotation causes the helical fastener28 to travel within the internal grooves 32 of the fastener applier andinto the graft 14 and vessel wall 34 FIG. 20. It is contemplated thatthe control assembly for the fastener applier could be activatedmechanically, electrically, hydraulically or pneumatically.

FIG. 21 illustrates a completed helical fastener 28 attachment of thegraft 14 to the vessel wall 34. It is contemplated that one or morefasteners will be required to provide secure attachment of the graft tothe vessel wall.

FIG. 22 illustrates a perspective view of a graft prosthesis attached tothe vessel wall both proximally and distally. It is contemplated thatthe present invention can be used for graft attachment of both straightand bifurcated grafts 15 within the aorta and other branch vessels.

It will be appreciated that the components and/or features of thepreferred embodiments described herein may be used together orseparately, while the depicted methods and devices may be combined ormodified in whole or in part. It is contemplated that the components ofthe directing device, fastener applier and helical fastener may bealternately oriented relative to each other, for example, offset,bi-axial, etc. Further, it will be understood that the variousembodiments may be used in additional procedures not described herein,such as vascular trauma, arterial dissections, artificial heart valveattachment and attachment of other prosthetic device within the vascularsystem and generally within the body.

The preferred embodiments of the invention are described above in detailfor the purpose of setting forth a complete disclosure and for the sakeof explanation and clarity. Those skilled in the art will envision othermodifications within the scope and sprit of the present disclosure.

1. A method for implanting a radially expandable prosthesis in a bodylumen, said method comprising: expanding at least one scaffold of theprosthesis at an implantation site within the body lumen; andintroducing a plurality of fasteners through the prosthesis in theregion of the scaffold to anchor the scaffold in place.